The invention relates to active adaptive control systems, and more particularly to a multi-filter-set system.
The invention arose during continuing development efforts directed toward active acoustic attenuation systems. Active acoustic attenuation involves injecting a canceling acoustic wave to destructively interfere with and cancel an input acoustic wave. In an active acoustic attenuation system, the input acoustic wave is sensed with an input transducer, such as a microphone or an accelerometer, which supplies an input reference signal to an adaptive filter control model. The output acoustic wave is sensed with an error transducer which supplies an error signal to the model. The model supplies a correction signal to a canceling output transducer, such as a loudspeaker or a shaker, which injects an acoustic wave to destructively interfere with the input acoustic wave and cancel or control same such that the output acoustic wave at the error transducer is zero or some other desired value.
An active adaptive control system minimizes an error signal by introducing a control signal from an output transducer to combine with the system input signal and yield a system output signal. The system input signal is sensed with an input transducer providing a reference signal. The system output signal is sensed with an error transducer providing an error signal. An adaptive filter model has a model input from the reference signal, an error input from the error signal, and outputs a correction signal to the output transducer to introduce the control signal matching the system input signal, to minimize the error signal.
The present invention is applicable to active adaptive control systems, including active acoustic attenuation systems. The present invention provides a system for implementing multichannel active control systems using multiple filters having multiple independent A/D and D/A converters. This system facilitates use of active control for applications requiring large amounts of processor computation time and/or memory by sharing the computational requirements between multiple controllers. The invention significantly reduces parallel processing requirements by using multi-filter-set combinations. The invention may be used to implement multichannel control systems such as shown in U.S. Pat. Nos. 5,216,721 and 5,216,722, incorporated herein by reference.